Variable data lithographic printing device and method

ABSTRACT

A variable data lithographic printing device comprises surrounding a printing cylinder a photosensitive layer coater, an exposure source, optionally a developer, an inking applicator, optionally a transfer system, and optionally an eraser. During printing operation, each surface areas of the rotating cylinder continuously undergo the cycle of coating, imagewise exposure, optionally developing, inking, printing of inked images to the receiving medium, and optionally erasing processes. The developing means can be omitted if an ink and/or fountain solution developable photosensitive layer is used. In an alternative design, the cylinder is replaced with a continuous supply of a ribbon with lithographic substrate surface. In another alternative design, the cylinder and the coater are replaced with a continuous supply of a pre-sensitized ribbon comprising on a substrate a photosensitive layer.

RELATED PATENT APPLICATIONS

[0001] This application is a division of U.S. patent application Ser.No. 10/162,345 filed Jun. 4, 2002.

FIELD OF THE INVENTION

[0002] This invention relates to variable data printing. Morespecifically, it relates to variable data lithographic printing deviceand process.

BACKGROUND OF THE INVENTION

[0003] Lithographic printing surface generally consists of ink-receptiveareas (image areas) and ink-repelling areas (non-image areas). Duringprinting operation, an ink is preferentially received in the imageareas, not in the non-image areas, and then transferred to the surfaceof a material upon which the image is to be produced.

[0004] Lithographic printing can be further divided into two generaltypes: wet lithographic printing and waterless lithographic printing. Inwet lithographic printing members, the ink-receptive areas consist ofoleophilic materials and the ink-repelling areas consist of hydrophilicmaterials; fountain solution (consisting of primarily water) is requiredto continuously dampen the hydrophilic materials during printingoperation to make the non-image areas oleophobic. In waterlesslithographic printing members, the ink-receptive areas consist ofoleophilic materials and the ink-repelling areas consist of oleophobicmaterials; no dampening with fountain solution is required.

[0005] At the present time, lithographic printing is generally performedon a lithographic printing press. The lithographic printing member canbe a typical lithographic printing plate mounted on the plate cylinder.The plate can be imaged and processed before or after mounted on press.Examples of such a printing process are described in U.S. Pat. Nos.5,700,619, 5,466,557, 5,491,045 and 5,955,238 (for off-press imaging andprocess), and U.S. Pat. Nos. 5,258,263, 5,395,734, 5,516,620, 6,030,750,6,014,929, 6,071,675, and 6,242,156 (for on-press development).

[0006] Alternatively, the lithographic printing member can be formed onpress by coating a photosensitive layer onto a plate cylinder surface oronto a plate substrate mounted on a plate cylinder. The on-press formedprinting member can be imagewise exposed and processed on press beforelithographic printing. After the completion of a printing operation, thehardened imaging layer on the plate cylinder can be cleaned off to allowreuse of the cylinder or substrate surface for preparing anotherprinting member. Such a printing system is commonly called platelesspress. Examples of such a plateless press are described in U.S. Pat.Nos. 5,713,287 and 6,298,780.

[0007] While lithographic printing process as described above has playeda major role in printing and publishing industrial for decades, theapplication of lithographic printing so far is limited to makingmultiple copies (usually a few hundreds to a few millions copies).

[0008] In variable data printing application wherein each copy printedhas different imaging, inkjet printing and electrophotographic (orcalled Xerox) laser printing are the most widely used methods, asevidenced by widely used desktop inkjet printer and laser printer. Otherprinting methods, such as thermal paper and thermal dye transfer, alsoplay an important role, as evidenced by some facsimile printers. Whilethese current variable data printing methods are very useful, theprinting quality by these methods is inferior to that by lithographicprinting in resolution, color density and imaging stability. Forexample, material printed with inkjet printer has limited resolution andimaging stability; material printed with thermal printer has limitedcolor density and imaging stability; and material printed with Xeroxlaser printer has limited resolution and toner-to-medium adhesion.

[0009] It would be desirable if a variable data printing device can bedesigned based on lithographic printing principle. This would allowimproved resolution, color density, and imaging stability.

SUMMARY OF THE INVENTION

[0010] It is an object of this invention to provide a lithographicprinting device suitable for variable data printing.

[0011] It is another object of this invention to provide a lithographicprinting device and process which allow continuous photosensitive layercoating, imagewise exposure, development, formation of inked imaging,transfer of the inked imaging to a receiving surface, and recovering ofthe substrate surface during printing process.

[0012] It is another object of this invention to provide a lithographicprinting device and process which allow continuous formation or supplyof pre-sensitized lithographic printing surface, imagewise exposure,development, formation of inked imaging, transfer of the inked imagingto a receiving surface during printing process.

[0013] Further objects, features and advantages of the present inventionwill become apparent from the detailed description of the preferredembodiments.

[0014] According to the present invention, there has been provided avariable data lithographic printing device comprising:

[0015] (a) a printing cylinder;

[0016] (b) a coating means for depositing a photosensitive layer on thecylinder surface, wherein said photosensitive layer is soluble ordispersible in ink and/or fountain solution, capable of hardening uponexposure to an actinic radiation, and exhibits an affinity or aversionsubstantially opposite to the affinity or aversion of said cylindersurface to at least one printing liquid selected from the groupconsisting of ink and an abhesive fluid for ink;

[0017] (c) an exposure means for providing the actinic radiation to thecylinder surface according to digital imaging information;

[0018] (d) an inking means for applying ink or both fountain solutionand ink to the cylinder surface; and

[0019] (e) an erasing means for removing the remaining photosensitivelayer and leftover ink to recover the cylinder surface;

[0020] (f) wherein the means (b) to (e) are mounted proximate thecylinder surface and sequentially arranged along the cylinder surface inthe rotating direction of the cylinder; and each means of (b) to (e)completes its designed function (coating, imaging, inking, or erasing)to the cylinder surface areas in the designed printing width which passby said means in each single pass during printing operation.

[0021] According to another aspect of the present invention, there hasbeen provided a method of variable data lithographic printing,comprising:

[0022] (a) providing a lithographic printing device as described above;

[0023] (b) continuously depositing the photosensitive layer on thecylinder surface;

[0024] (c) continuously exposing the plate with an actinic radiation tocause hardening of the photosensitive layer in the exposed areasaccording to digital imaging information;

[0025] (d) continuously applying ink or both fountain solution and inkto the cylinder surface to remove the non-hardened areas of thephotosensitive layer and to form inked imaging on the cylinder surface;

[0026] (e) continuously lithographically printing images from saidcylinder surface to a receiving surface; and

[0027] (f) continuously removing the hardened photosensitive layer andleftover ink to bare the cylinder surface.

[0028] The above printing systems can be designed in a way so that thehardened photosensitive layer is capable of transferring with ink to thereceiving surface, or the hardened photosensitive layer and leftover inkare capable of dissolving or dispersing into the photosensitive layercoating fluid from the coating means. In either system, the erasingmeans can be omitted.

[0029] For the above variable data lithographic printing device of thisinvention, the printing cylinder can be replaced with a substrate ribbonsupply means for passing a ribbon having a lithographic substratesurface through one or more rollers with one end unwinding from a rollof unused ribbon and the other end winding up to a roll of used ribbon.The erasing means is not needed in such a system. The coating means,exposure means, and inking means are mounted proximate the passage ofthe ribbon and sequentially arranged along the moving direction of theribbon.

[0030] For the above variable data lithographic printing device of thisinvention, the printing cylinder and the coating means can be replacedwith a pre-sensitized lithographic ribbon supply means for passing apre-sensitized lithographic ribbon through one or more rollers with oneend unwinding from a roll of unused ribbon and the other end winding upto a roll of used ribbon, wherein the pre-sensitized ribbon comprises ona substrate an ink and/or fountain solution developable photosensitivelayer. The erasing means is not needed. The exposure means and inkingmeans are mounted proximate the passage of the ribbon and sequentiallyarranged along the moving direction of the ribbon.

[0031] For all the above devices and processes of this invention, adeveloping means can be added between the exposure means and inkingmeans so that a conventional photosensitive layer that is notdevelopable with ink and/or fountain solution can be used.

[0032] The printing device of this invention can be a typical printerwherein the inked imaging is transferred to a sheet-like receivingmedium that passes through the printing device; a transfer means can beequipped after the inking means to feed the receiving medium through theprinting device while pressing the receiving medium against the inkedcylinder or ribbon surface. Alternatively, the printing device of thisinvention can be a printing wheel wherein the printing cylinder orprinting device moves against the receiving surface of a stationaryobject during printing operation.

[0033] The current invention can be used to design various variable dataprinters such as desktop printer, portable printer, photoprinter,photocopier, facsimile printer, cashier receipt printer, and variabledata printing wheels. The variable data printing wheels are suitable forprinting variable imaging on various fixed or hard-to-feed objects suchas floor, wall, road, box, a page in a book, truck, clothes, cardboard,skin, and billboard.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention utilizing a cylinder with lithographicsubstrate surface and an ink and/or fountain solution developablephotosensitive coating.

[0035]FIG. 2 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention wherein the non-hardened areas of thephotosensitive layer are removed by the developing means.

[0036]FIG. 3 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention wherein the receiving medium passesthrough the printing device.

[0037]FIG. 4 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention wherein the printing cylinder movesagainst a stationary object to be printed during printing process. Sucha device is also called printing wheel.

[0038]FIG. 5 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention wherein the hardened areas of thephotosensitive layer transfer with ink to the receiving surface.

[0039]FIG. 6 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention wherein the hardened photosensitivelayer and leftover ink are dissolved or dispersed in the coating fluidfrom the coating means.

[0040]FIG. 7 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention utilizing a ribbon to form thelithographic substrate surface.

[0041]FIG. 8 is a diagrammatic cross-sectional view of a lithographicprinting device of the invention utilizing a pre-sensitized lithographicribbon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The lithographic printing device utilizing a cylinder to form thelithographic substrate surface and an ink and/or fountain solutiondevelopable photosensitive layer is illustrated in FIG. 1. Thelithographic printing device comprises (i) a cylinder 10 having anexternal substrate surface; (ii) a coating means 12, (iii) an exposuremeans 14, (iv) an inking means 18 capable of delivering ink or bothfountain solution and ink, and (v) an erasing means 22 capable ofrecovering the substrate surface. The means 12, 14, 18, and 22 aremounted proximate the cylinder surface and sequentially arranged alongthe cylinder surface in the rotating direction of the cylinder; and eachmeans of 12, 14, 18, and 22 completes its designed function (coating,exposure, inking, or erasing) to the cylinder surface areas at thedesigned printing width which pass by that means in each single passduring printing operation. Between the coating means and the erasingmeans, the cylinder should have an open surface area available fortransferring the inked imaging to the receiving surface. A transfermeans, such as a roller transporting the medium while pressing againstthe cylinder, may be equipped. A photosensitive layer suitable for usein such a device must be soluble or dispersible in and quicklydevelopable with ink and/or fountain solution.

[0043] All the figures in this patent are high level illustrations. Eachmeans can be a single element or a combination of multiple elements, asneeded for performing the desired function. For example, the inkingmeans can be a single ink roller, or can be a combination of three inkrollers and two fountain solution rollers. In all the figures, thephotosensitive layer is illustrated as ink-receptive. However, thephotosensitive layer can also be ink-repelling with the substrate beingink-receptive.

[0044] During printing operation as also illustrated in FIG. 1, thecoating means 12 applies coating fluid 30 to the surface of the cylinder10. The exposure means 14 exposes the photosensitive layer with anactinic radiation according to digital imaging information to formhardened areas 32 (exposed areas) and non-hardened areas 34 (non-exposedareas). The inking means 18 applies ink (for waterless lithographicprinting surface) or both fountain solution and ink (for wetlithographic printing surface) to remove the non-hardened areas of thephotosensitive layer and to form inked imaging 36. The inked imaging 36is transferred to the surface of the receiving object 50 to form printedimaging 38. The cured photosensitive layer and any leftover ink arecleaned off with the erasing means 22. The erasing means may use a dryprocess such as cleaning with a blade or brush or a wet process such aswiping with a ribbon soaked with solvent, and a collecting means may beequipped to collect the removed photosensitive layer and leftover ink aswell as any waste solvent. For waterless lithographic printing surface,the inking means 18 applies only ink. For wet lithographic printingsurface, the inking means 18 applies both fountain solution and ink,preferably with fountain solution being applied first followed by ink orwith both fountain solution and ink being applied together as emulsion;alternatively, a single fluid ink suitable for wet lithographic printingsurface can be used.

[0045] A developing means may be installed between the exposure meansand the inking means, as illustrated in FIG. 2. A lithographic printingdevice comprising a developing means allows the utilization of aphotosensitive layer that is not developable with ink and/or fountainsolution. Such a lithographic printing device comprises (i) a cylinder10 having an external substrate surface; (ii) a coating means 12, (iii)an exposure means 14, (iv) a developing means 16, (v) an inking means 18capable of delivering ink or both fountain solution and ink, and (vi) anerasing means 22 capable of recovering the substrate surface. The means12, 14, 16, 18, and 22 are mounted proximate the cylinder surface andsequentially arranged along the cylinder surface in the rotatingdirection of the cylinder; and each means of 12, 14, 16, 18, and 22completes its designed function (coating, exposure, developing, inking,or erasing) to the cylinder surface areas at the designed printing widthwhich pass by that means in each single pass during printing operation.A transfer means, such as a roller transporting the medium whilepressing against the cylinder, may be equipped. During printingoperation, the coating means 12 applies coating fluid 30 to the surfaceof the cylinder 10. The exposure means 14 exposes the photosensitivelayer with an actinic radiation according to digital imaging informationto form hardened areas 32 (exposed areas) and non-hardened areas 34(non-exposed areas). The areas 34 not exposed with the actinic radiationare removed by developing means 16. The developed cylinder surface isapplied with ink or both fountain solution and ink with the inking means18 to form inked imaging. The inked imaging 36 is transferred to thesurface of the receiving object 50 to form printed imaging 38. Thehardened photosensitive layer and leftover ink are cleaned off with theerasing means 22.

[0046] It is a key requirement of this invention that each meanssurrounding the printing cylinder, such as 12, 14, 16, 18, 20 and 22,completes its designed function to the cylinder surface areas in thedesigned printing width which pass by that means in each single passduring printing operation. In other words, whenever any surface areas ofthe cylinder in the designed printing width pass by a means, that meansimmediately carries out and completes its designed function (such ascoating, exposure, developing, inking, printing, or erasing) to theseareas. All the surface areas of the cylinder at the designed printingwidth complete a full cycle of functions (such as coating, exposure,developing, inking, printing, and erasing) for each rotation duringregular printing operation.

[0047] The term designed printing width means the width of the imagingpattern (including inked and non-inked areas) to be printed from thecylinder to the receiving object. The designed printing width can be thefull length of the cylinder, or can be a specific width (which is lessthan the full length of the cylinder) along the axis direction of thecylinder. A printing device can have a fixed printing width, or theprinting width can be adjusted for different printing job. Usually allthe means effectively cover the same width which is the designedprinting width. However, certain means, such as exposure means andinking means, may cover narrower areas than other means; and certainmeans, such as the erasing means, may cover wider areas than othermeans. The narrower covering width for certain means is desirable whenthe width of a printing job is narrower than the maximum or typicalprinting width of the printing device and when it is more feasible toonly adjust the covering width of some of the means.

[0048] While each means is utilized to perform a specific function, thespecific design of that means is not limited. In this invention, anydesign that can perform the specific function of a means can be used forthat means. For example, the coating means can be a roller coater, slotcoater, or a spray coater; the dampening means can apply fountainsolution by spraying or by using a roller; and the erasing means canrecover the substrate surface by removing the photosensitive layer andthe leftover ink with a blade or by wiping with a cloth or ribbon soakedwith a solvent or solution.

[0049] Usually, all the means performs their functions during the wholeprinting process, even when printing a large continuous non-inked area(such as a third of a page). Alternatively, for a large area where thefunction performed by certain means is not necessary, the means may beturned off or disengaged from the cylinder surface, preferably by anautomatic or digital means. For example, if a third of a page ofprinting area is non-inked area, the inking means may be disengaged fromthe cylinder surface or the coating means may pause coating onto thecylinder surface corresponding to this area. The receiving surface maybe disengaged from the printing cylinder to let the cylinder and all themeans operate in idle during the startup of a printing job (to tune upthe printing process) or when there is a large continuous non-inkedareas (such as half a page). For multicolor printing machine equippedwith two or more printing cylinders as well as other means around thecylinders, one (or more) of the printing cylinders may be disengagedfrom the receiving surface if that color is not used in the particularprinting job or in a large continuous area.

[0050] The cylinder rotating speed is usually constant during oneprinting operation. However, it may be automatically adjusted accordingto the imaging density. It may rotate faster for lower imaging densityand slower for higher imaging density.

[0051] The printing cylinder can have any dimensions suitable forcarrying out the lithographic printing process of this invention. Theprinting cylinder preferably has a diameter of from 0.2 to 1000 cm, morepreferably from 1 to 100 cm, and most preferably from 2 to 50 cm. Fordesktop printers, the printing cylinder diameter is relatively smaller,preferably ranging from 0.5 to 50 cm, and more preferably from 1 to 20cm. For portable printers, the printing cylinder diameter can be evensmaller, preferably ranging from 0.2 to 20 cm, and more preferably from0.5 to 10 cm. For printing presses, the printing cylinder diameter isrelatively larger, preferably ranging from 10 to 200 cm, and morepreferably from 20 to 100 cm. For printing wheels, the printing cylinderdiameter can be similar to that for a desktop printer or similar to thatfor a printing press, or can be even larger. The printing cylinder in aprinting wheel device can be relatively small in diameter so that it caneasily reach out to print various surfaces, such as a wall. The wholeprinting wheel device can be relatively small so that it can be carriedby hand to perform the printing job on a surface, such as a wall orfloor. Alternatively, the printing cylinder in a printing wheel devicecan be a large wheel (such as from 10 to 1000 cm in diameter) on avehicle and is driven by the vehicle during printing operation (such asprinting a floor or a road).

[0052] The cylinder surface can be made of any material that is suitablefor the substrate surface for lithographic printing. The cylindersurface can be an integrated part of the cylinder, or can be the surfaceof a plate or sleeve slid onto the cylinder. The cylinder surface can bemade of, for example, a metal, a polymer, glass, or a ceramic. A surfacecoating or surface treatment may be applied to the material on thecylinder surface to achieve desired surface properties. The printingcylinder preferably has a seamless surface. The cylinder surface can besmooth or microscopically roughened.

[0053] Suitable hydrophilic materials for the cylinder surface include,for example, anodized aluminum, chrome, nickel, steel, glass, andceramics (such as alumina and zirconia). A preferred hydrophiliccylinder surface is made of a metal or metal alloy, including steel andaluminum, which has been anodized and deposited with a hydrophilicbarrier layer. The metal or metal alloy may have smooth or grainedsurface. Surface graining (or roughening) can be achieved by mechanicalgraining or brushing, chemical etching, and/or AC electrochemicalgraining. The roughened surface can be further anodized to form adurable aluminum oxide surface using an acid electrolyte such assulfuric acid and/or phosphoric acid. The roughened and anodizedaluminum surface can be further thermally or electrochemically coatedwith a layer of silicate or hydrophilic polymer to form a durablehydrophilic layer. A second preferred hydrophilic cylinder surface is aceramic or glass that has smooth or roughened microscopic surface. Apreferred oleophilic cylinder surface comprises an oleophilic polymericmaterial.

[0054] The photosensitive layer of the current invention can be anymaterial capable of hardening upon exposure to an actinic radiation inultraviolet, visible, or infrared region (about 200 to 1500 nm inwavelength). Hardening means becoming insoluble in a suitable developer.For ink and/or fountain solution developable photosensitive layer,hardening means becoming insoluble in ink and/or fountain solution.Suitable photosensitive materials include, for example,photopolymerizable compositions, silver halide emulsions, and diazoniumsalts. For infrared sensitive photosensitive materials, infraredabsorbing dye or pigment can be added. Various additives may be added,such as surfactant, plasticizer, viscosity reducer, stabilizer, dye, orpigment. The photosensitive layer may be colorless or may have the samecolor of the ink by adding a suitable dye or pigment. Preferredphotosensitive materials are free radical or cationic polymerizablecompositions. The photosensitive layer is preferably deposited from aliquid photosensitive coating with or without addition of solvent. Herethe term solvent includes organic solvent and water. The photosensitivelayer preferably has a coverage of 0.02 to 2.0 g/m², more preferably 0.1to 1.5 g/m², and most preferably 0.2 to 1.0 g/m².

[0055] The photosensitive layer can comprise a polymerizable monomer anda photoinitiator. A sensitizer (such as an infrared, visible, orultraviolet light absorbing dye) may be added to allow sensitivity to acertain radiation (such as an infrared, visible, or ultraviolet light).The term monomer includes both monomer and oligomer capable ofpolymerization.

[0056] A preferred photosensitive layer comprises a polymerizableethylenically unsaturated monomer and a free-radical photoinitiator; asecond preferred photosensitive layer comprises a vinyl ether or epoxymonomer and a cationic photoinitiator. Polymeric binder, sensitizingdye, and/or various other additives may be added. Here thephotosensitive layer can be sensitized to ultraviolet, visible, orinfrared radiation.

[0057] A preferred infrared sensitive photosensitive layer comprises apolymerizable ethylenically unsaturated monomer, a free-radicalinitiator, and an infrared absorbing dye; a second preferred infraredsensitive photosensitive layer comprises a vinyl ether or epoxy monomer,a cationic initiator, and an infrared absorbing dye. Polymeric binder,and/or various other additives may be added.

[0058] Semisolid photosensitive materials as described in U.S. Pat.application Ser. No. 09/873,598 and thermosensitive materials asdescribed in U.S. Pat. application Ser. Nos. 09/656,052, 09/699,784,09/952,933, and 10/023,342 can be used for the photosensitive layer ofthis invention. The entire disclosures of U.S. Pat. application Ser.Nos. 09/873,598, 09/656,052, 09/699,784, 09/952,933, and 10/023,342 arehereby incorporated by reference.

[0059] Suitable free-radical polymerizable monomers include, forexample, multifunctional (meth)acrylate monomers (such as (meth)acrylateesters of ethylene glycol, trimethylolpropane, pentaerythritol,ethoxylated ethylene glycol and ethoxylated trimethylolpropane,multifunctional urethanated (meth)acrylate, and epoxylated(meth)acrylate), and oligomeric amine diacrylates. The (meth)acrylicmonomers may also have other double bond or epoxide group, in additionto (meth)acrylate group. The (meth)acrylate monomers may also contain anacidic (such as carboxylic acid) or basic (such as amine) functionality.

[0060] Suitable free-radical initiators include, for example,derivatives of acetophenone (such as 2,2-dimethoxy-2-phenylacetophenone,and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one);benzophenone; benzil; ketocoumarin (such as 3-benzoyl-7-methoxy coumarinand 7-methoxy coumarin); xanthone; thioxanthone; benzoin or analkyl-substituted anthraquinone; onium salts [such as diaryliodoniumhexafluoro antimonate, diaryliodonium triflate,(4-(2-hydroxytetradecyl-oxy)-phenyl)phenyl iodoniumhexafluoroantimonate, triarylsulfonium hexafluorophosphate,triarylsulfonium p-toluenesulfonate, (3-phenylpropan-2-onyl) triarylphosphonium hexafluoroantimonate, and N-ethoxy(2-methyl)pyridiniumhexafluorophosphate, and the onium salts as described in U.S. Pat. Nos.5,955,238, 6,037,098, and 5,629,354]; borate salts [such astetrabutylammonium triphenyl(n-butyl)borate, tetraethylammoniumtriphenyl(n-butyl)borate, diphenyliodonium tetraphenylborate, andtriphenylsulfonium triphenyl(n-butyl)borate, and the borate salts asdescribed in U.S. Pat. Nos. 6,232,038 and 6,218,076]; haloalkylsubstituted s-triazines [such as2,4-bis(trichloromethyl)-6-(p-methoxy-styryl)-s-triazine,2,4-bis(trichloromethyl)-6-(4-methoxy-naphth-1-yl)-s-triazine,2,4-bis(trichloromethyl)-6-piperonyl-s-triazine, and2,4-bis(trichloromethyl)-6-[(4-ethoxyethylenoxy)-phen-1-yl]-s-triazine,and the s-triazines as described in U.S. Pat. Nos. 5,955,238, 6,037,098,6,010,824, and 5,629,354]; and titanocene[bis(η⁹-2,4-cyclopentadien-1-yl)bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl) titanium]. The initiator isadded in the photosensitive layer preferably at 0.1 to 40% by weight ofthe photosensitive layer, more preferably at 0.4 to 20%, and mostpreferably at 1 to 10%.

[0061] Suitable polyfunctional epoxy monomers include, for example,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,bis-(3,4-epoxycyclohexymethyl) adipate, difunctional bisphenolA/epichlorohydrin epoxy resin and multifunctionalepichlorohydrin/tetraphenylol ethane epoxy resin.

[0062] Suitable cationic photoinitiators include, for example,triarylsulfonium hexafluoroantimonate, triarylsulfoniumhexafluorophosphate, diaryliodonium hexafluoroantimonate, and haloalkylsubstituted s-triazine. It is noted that most cationic initiators arealso free radical initiators because, in addition to generating Bronstedacid, they also generate free radicals during photo or thermaldecomposition.

[0063] Infrared absorbers useful in the infrared sensitivephotosensitive layer of this invention include any infrared absorbingdye or pigment effectively absorbing an infrared radiation having awavelength of 700 to 1,500 nm. It is preferable that the dye or pigmenthas an absorption maximum between the wavelengths of 750 and 1,200 nm.Various infrared absorbing dyes or pigments are described in U.S. Pat.Nos. 5,858,604, 5,922,502, 6,022,668, 5,705,309, 6,017,677, and5,677,106, and in the book entitled “Infrared Absorbing Dyes” edited byMasaru Matsuoka, Plenum Press, New York (1990), and can be used in theinfrared sensitive photosensitive layer of this invention. Examples ofuseful infrared absorbing dyes include squarylium, croconate, cyanine(including polymethine), phthalocyanine (including naphthalocyanine),merocyanine, chalcogenopyryloarylidene, oxyindolizine, quinoid,indolizine, pyrylium and metal dithiolene dyes. Cyanine andphthalocyanine dyes are preferred infrared absorbing dyes. Examples ofuseful infrared absorbing pigments include black pigments, metal powderpigments, phthalocyanine pigments, and carbon black. Carbon black is apreferred infrared absorbing pigment. Mixtures of dyes, pigments, orboth can also be used. Infrared absorbing dye is preferred over infraredabsorbing pigment because the infrared absorbing dye usually has higherabsorbing efficiency, gives less visible color, and allows molecularlevel charge or energy transfer to activate the initiator. The infrareddye or pigment is added preferably at 0.01 to 30% by weight of theinfrared sensitive photosensitive layer, more preferably at 0.1 to 20%,and most preferably at 0.5 to 10%.

[0064] Suitable polymeric binders for the photosensitive layers of thisinvention include, for example, polystyrene, (meth)acrylic polymers andcopolymers (such as polybutylmethacrylate, polyethylmethacrylate,polymethylmethacrylate, polymethylacrylate, andbutylmethacrylate/methylmethacrylate copolymer), polyvinyl acetate,polyvinyl chloride, styrene/acrylonitrile copolymer, nitrocellulose,cellulose acetate butyrate, cellulose acetate propionate, vinylchloride/vinyl acetate copolymer, partially hydrolyzed polyvinylacetate, polyvinyl alcohol partially condensation-reacted withacetaldehyde, butadiene/acrylonitrile copolymer, and polyurethane. Thepolymers may or may not have polymerizable functional groups (such asethylenic group, epoxy group, or vinyl ether group).

[0065] The ink and/or fountain solution developable photosensitive layerof this invention must be capable of hardening upon exposure to anactinic radiation, and soluble or dispersible in ink and/or fountainsolution and can be developed off quickly with ink and/or fountainsolution. Various ink and/or fountain solution developablephotosensitive layers have been disclosed in the patent literature suchas U.S. Pat. Nos. 5,516,620, 5,677,108, 5,776,654, 5,811,220, 5,997,993,6,014,929, 6,071,675 and 6,027,857, and can be used in this invention.Because the photosensitive layer is in situ coated and there is nohandling issue, liquid or semisolid photosensitive compositions can beused. Higher amount of liquid monomer can be used in the photosensitivelayer.

[0066] For ink and/or fountain solution developable photosensitivelayer, various surfactants may be added into the photosensitive layer toallow or enhance the ink and/or fountain solution developability. Bothpolymeric and small molecule surfactants can be used. However, it ispreferred that the surfactant has low or no volatility so that it willnot evaporate from the photosensitive layer. Nonionic surfactants arepreferred. Preferred nonionic surfactants are polymers and oligomerscontaining one or more polyether (such as polyethylene glycol,polypropylene glycol, and copolymer of ethylene glycol and propyleneglycol) segments. Examples of preferred nonionic surfactants are blockcopolymers of propylene glycol and ethylene glycol; ethoxylated orpropoxylated acrylate oligomers; and polyethoxylated alkylphenols andpolyethoxylated fatty alcohols. The nonionic surfactant is preferablyadded at 0.1 to 30% by weight of the photosensitive layer, morepreferably 0.5 to 20%, and most preferably 1 to 10%.

[0067] The photosensitive layer is deposited from a coating material bythe coating means. The coating material is preferably a liquid orsemisolid material capable of forming a thin film on the cylindersurface by a suitable coating means. The coating means can be in anyform. Examples of suitable coating means include roller coater, slotcoater, sponge coater, and spray coater. The coating material ispreferably stored in a reservoir, and the coating means continuouslytransfers the coating material to the cylinder surface at a certain rateduring printing operation. For example, the coating means can be aroller that is in contact with the coating material reservoir in onerotating angle and with the printing cylinder in another rotating angle;during printing operation, the roller continuously rotates to deliverthe coating material to the cylinder surface to form a thinphotosensitive layer. The reservoir containing the coating material maybe supplied as coating material cartridge. Alternatively the coatingmaterial in the reservoir may be refillable. The coating roller and thereservoir may be built as an integrated part, or can be built asseparate parts. The integrated coating unit comprising the coatingroller and the reservoir containing coating material may be supplied asa coating cartridge.

[0068] The coating material is usually coated at room or environmentaltemperature. Alternatively, the coating material may be heated by aheating means within the coating means to reduce viscosity and allowthinner coating; this allows the use of certain higher viscosity liquidor semisolid, or even solid coating material.

[0069] The coating material for forming the photosensitive layer ispreferably free of solvent and is preferably a liquid or semisolidmaterial. However, solvent may be added to facilitate the coatingprocess. For photosensitive layer deposited from a coating with solvent,a drying means can be equipped next to the coating means. Examples ofsuitable drying means include a device providing forced room-temperatureor hot air.

[0070] The photosensitive material is preferably deposited on theprinting cylinder surface as a single layer. However, more than onephotosensitive layers deposited from two or more coaters next to eachother may be applied. A photo-insensitive overcoat may be applied overthe photosensitive layer by an overcoat coater after the photosensitivelayer coating means to, for example, reduce oxygen inhibition andimprove photospeed. A photo-insensitive interlayer may be applied to thecylinder surface by an interlayer coater before coating thephotosensitive layer. For printing device using ink and/or fountainsolution developable photosensitive layer, ink and/or fountain solutionsoluble or dispersible overcoat and interlayer should be used.

[0071] The exposure means provides imaging radiation to thephotosensitive layer in the areas passing by the exposure means in thedesigned printing width according to digital imaging information. Theradiation is capable of causing hardening of the photosensitive layer.It can be an infrared, visible, or ultraviolet radiation that is actinicto the photosensitive layer. The radiation can be from any source,including a laser, LED, or conventional light source. Laser is apreferred radiation source. Laser diodes are especially useful becauseof their small sizes and relatively low costs. Preferred visible orultraviolet light lasers include, for example, frequency-doubled Nd/YAGlaser, argon ion laser, violet diode laser, and ultraviolet laser.Preferred infrared lasers are laser diodes emitting around 830 nm orNd/YAG laser emitting around 1060 nm. The exposure dosage is preferablyabout 0.001 to about 1000 mJ/cm², and more preferably about 0.1 to about500 mJ/cm², depending on the sensitivity of the photosensitive layer.Exposure dosage should be high enough to give sufficient hardening sothat the hardened photosensitive layer can withstand the developmentand/or inking action, but it should be preferably low enough so that thehardened photosensitive layer is not too hard to be removed by theerasing means. The suitable dosage should depend on the specificphotosensitive layer, cylinder surface, developing process, inkingprocess, erasing process, and/or the general design of the printingdevice.

[0072] The exposure means can cover the designed printing width by, forexample, scanning back and forth a laser with a rotating mirror alongthe axis direction of the printing cylinder to expose the cylindersurface passing by according to digital imaging information, orutilizing an array of digitally controlled lasers or LEDs to cover thefull printing width. Laser scanners using a rotating mirror for scanningback and forth along the axis direction have been well described in thepatents, and can be used for the exposure means of this invention.Examples of such laser scanners are described in U.S. Pat. Nos.5,235,454, 5,124,830, 5,428,473, and 5,142,404.

[0073] The developing means applies a developer liquid to thephotosensitive layer to dissolve or disperse and remove the non-hardenedareas of the photosensitive layer. The developing means can be in anyform. For example, it can be a cloth or ribbon soaked with the developerliquid that wipes over the cylinder surface during printing process. Theused cloth or ribbon may be replaced automatically through automaticmeans during printing operation; for example, the ribbon can be verylong with one end unwinding from a roll of clean ribbon and the otherend winding up to a roll of dirty ribbon. For printing device using anink and/or fountain solution developable photosensitive layer, thedeveloping means is not needed.

[0074] The inking means applies ink or both fountain solution and ink tothe cylinder surface. It is preferably applied through one or morerollers. The inking means preferably has a reservoir of ink or both areservoir of ink and a reservoir of fountain solution. During printingoperation, the roller rotates and transfers the ink or both fountainsolution and ink to the cylinder surface. For waterless lithographicprinting surface, only ink is used. For wet lithographic printingsurface, both fountain solution and ink are used, except for therecently introduced single fluid ink that allows printing on wetlithographic surface without the use of fountain solution. For inkingmeans carrying both fountain solution and ink, usually the fountainsolution is applied first followed by the ink. Alternatively, thefountain solution and ink are emulsified by the inking rollers and thentransferred as emulsion of fountain solution and ink to the cylindersurface. For photosensitive layer developable with ink or both fountainsolution and ink, the inking means removes the photosensitive layer inthe non-hardened areas, and then inks up the ink-receptive areas, suchas the hardened areas. The ink roller is pressed against the cylindersurface at a suitable pressure. Certain movement of the ink rollers,such as movement along the axial direction, vibration, or shearingagainst the rotating surface of the printing cylinder may be used toenhance the ink and/or fountain solution development as well as theinking process.

[0075] The ink suitable for the lithographic printing device of thepresent invention is generally an oleophilic, pigmented liquid orsemisolid material, and is similar to or the same as the ink used inlithographic printing press; an oleophilic ink forms inked imaging inthe oleophilic areas. However, a dyed or colorless ink may be used. Ahydrophilic ink may also be used to form inked imaging in thehydrophilic areas. The ink can be non-radiation curable or radiationcurable. Non-radiation curable ink has the advantage of lower cost andnot requiring curing device. Radiation curable ink allows immediatedrying of the ink and better stability on the receiving surface. Theradiation can be an ultraviolet, visible, or infrared light, dependingon the sensitization of the ink. Ultraviolet curable ink is thepreferred radiation curable ink. When a radiation curable ink is used, alamp may be installed in the printing device facing the just printedreceiving surface to cure the printed ink.

[0076] For a wet lithographic printing surface utilizing both fountainsolution and ink, the photosensitive ink and the photosensitive layermay be formulated to have the same or substantially the samecomposition. Pigment or dye may be added to the photosensitive layer.This allows minimized cross contamination.

[0077] The printing device of this invention can be a regular printerwith the receiving medium passing through the printer, as illustrated inFIG. 3, wherein a transfer means 20 is equipped to pass the receivingmedium 50 through the printing device at the moving speed of thecylinder surface while pressing the receiving medium 50 against theinked cylinder surface 36. Alternatively, the printing device of thisinvention can be a printing wheel, as illustrated in FIG. 4, wherein theprinting cylinder 10 or printing device moves against the receivingsurface of a stationary object 55 to form inked imaging 38 on thereceiving surface. The cylinder should have certain open surface areasthat allow direct contact of the inked cylinder surface 36 with thereceiving object 55. The printing wheel should move at the moving speedof the cylinder surface. The movement of the printing wheel duringprinting process may be controlled manually or by an automatically ormanually operated mechanical device.

[0078] The inked imaging is preferably transferred directly from theprinting cylinder to a receiving surface. Alternatively, the inkedimaging can be transferred to an intermediate cylinder that transfersthe inked imaging to the receiving surface; the intermediate cylinder isequipped with a cleaning means to clean off any leftover ink. Forprinting device with two or more printing cylinders, two or moreprinting cylinders may share the same intermediate cylinder to transferthe imaging from these printing cylinders to the receiving surface.Alternatively, a transfer belt or disposable ribbon can be used in placeof the intermediate cylinder to transfer the inked imaging to thereceiving surface.

[0079] The erasing means removes the hardened areas of thephotosensitive layer and any leftover ink from the cylinder surface, andprepares the cylinder surface for next cycle of processes starting withcoating. Any debris attracted to the cylinder surface during theprevious printing cycle, such as dust attracted from the receivingsurface, is also removed by the erasing means. The erasing means can bein any form, such as a blade (suitable for a flat substrate surface), ora cloth, ribbon or belt dampened with a cleaning solvent. The used clothor ribbon may be replaced automatically through automatic means duringprinting operation; for example, the ribbon can be very long with oneend unwinding from a roll of clean ribbon and the other end winding upto a roll of dirty ribbon. The belt may pass through a cleaning solventthat cleans off the belt and allows reuse of the belt. A collectingmeans such as a vacuum or a box may be equipped next to the blade tocollect the removed materials.

[0080] The printing device of this invention may be designed in a way sothat the hardened photosensitive layer is capable of transferring withink to the receiving surface. Such a printing device is illustrated inFIG. 5. In such a system, the erasing means may be omitted, although itis preferred to still have an erasing means in place in order to cleanup any accidentally non-transferred photosensitive layer or to clean upthe photosensitive layer when the printing device is running in idle(without printing to a receiving medium). Such a system may be achievedthrough certain modification of the printing system. It may be achievedby designing the photosensitive layer, the ink, the cylinder surface,and/or the receiving surface in a way so that the adhesion between thehardened photosensitive layer and the substrate is less than theadhesion between the hardened photosensitive layer and the receivingsurface. The adhesion of the ink to the receiving surface and/or to thehardened photosensitive layer may be modified during the printingprocess by radiation, heat, solvent evaporation, chemical reaction,pressure, and any other physical or chemical process. In order for thehardened photosensitive layer to transfer with the ink to the receivingmedium, the adhesion between the hardened photosensitive layer and thecylinder surface should not be too strong. On the other hand, theadhesion can not be too week because poor adhesion will cause lift-offof the hardened areas of photosensitive layer during development and/orinking process. Preferably, the cylinder surface has a smooth orshallowly grained surface.

[0081] A radiation curable ink that gives increased adhesion to thehardened photosensitive layer and/or the receiving surface upon exposureto a radiation can be used. A light source, preferably a lamp, may beinstalled in the printing device to irradiate the ink to cause partialor full curing before or during the transfer of the ink to the receivingmedium. The light source can be installed between the inking means andthe transfer point of the ink to the receiving surface; a deflector maybe used to prevent the light from reaching the inking means.Alternatively, the light source can be installed after the transferpoint of the ink to the receiving surface and exposes the ink on thetransfer point.

[0082] A heat-sensitive ink which gives increased adhesion to thehardened photosensitive layer and/or the receiving surface upon heatingcan also be used. The increase in adhesion upon heating may be caused bychemical changes (such as thermal curing) or physical changes (such asthermal flow). A hot roller may be used to heat the ink by pressing thereceiving medium against the cylinder surface. Alternatively, hot air orradiation may be used to heat the ink.

[0083] The printing device of this invention may be designed in a way sothat the hardened photosensitive layer and leftover ink 40 can bedispersed or dissolved in the photosensitive layer coating fluid fromthe coating means 12, as illustrated in FIG. 6. In such a system, theerasing means can be omitted. The photosensitive layer coating fluidshould be designed to be robust enough so that the dispersion ordissolution of the hardened photosensitive layer and leftover ink in thecoating fluid does not significantly interfere with the performance ofthe photosensitive layer. The ink should be designed to be compatiblewith the coating fluid so that the leftover ink does not interfere withthe performance of the photosensitive layer. A photohardenable ink withphotosensitivity similar to or even higher than that of thephotosensitive layer can be used to minimize the interference of thehardened photosensitive layer and leftover ink to the photosensitivelayer. For a wet lithographic printing process, the photosensitive inkand the photosensitive layer can be formulated to have the same orsubstantially the same composition; pigment or dye can be added to thephotosensitive layer. The photosensitive layer should be only partiallyhardened by the exposure means so that the hardened photosensitive layerbecomes insoluble or non-dispersible in ink and/or fountain solution butremains soluble or dispersible in the coating fluid. The coating fluidshould be designed to have more dissolving power than the ink and/orfountain solution. The coating means may be designed to be able todissolve or disperse and then mix the hardened photosensitive layer andleftover ink with the coating fluid. For example, one or more rollersmay be used to perform dissolution or dispersion and mixing actions;preferably, two or more rollers are used. The hardened photosensitivelayer and leftover ink may mix with small amount of coating fluid thatis being applied, or large amount of coating fluid, or even the wholereservoir of coating fluid in the coating means. The photosensitivelayer coating fluid can be a solventless liquid material, or can be asolution or dispersion with addition of solvent.

[0084] The lithographic printing device of this invention utilizing asubstrate ribbon supply means is illustrated in FIG. 7. The lithographicprinting device comprises (i) a substrate ribbon supply means forpassing a ribbon 62 having a lithographic substrate surface through oneor more rollers 64 (or cylinders 66) with one end unwinding from a rollof unused ribbon 60 and the other end winding up to a roll of usedribbon 70, (ii) a coating means 12 capable of depositing aphotosensitive layer, (iii) an exposure means 14, and (iv) an inkingmeans 18 capable of delivering ink or both fountain solution and ink.Here the term roller includes both roller and cylinder. Optionally, atransfer means 20 (not shown here) capable of transferring the inkedimaging to the receiving surface can be installed after the inkingmeans. Such a device requires an ink and/or fountain solutiondevelopable photosensitive layer. For a photosensitive layer notdevelopable with ink and/or fountain solution, a developing means 16(not shown here) may be installed between the exposure means and theinking means. The means 12, 14, 16, 18, and 20 are mounted proximate theribbon and sequentially arranged along the moving direction of theribbon; and each means of 12, 14, 16, 18, and 20 completes its designedfunction (such as coating, imaging, developing, inking, or transfer) tothe ribbon surface areas at the designed printing width which pass bythat means in each single pass during printing operation.

[0085] The lithographic printing device of this invention utilizing apre-sensitized lithographic ribbon is illustrated in FIG. 8. Thelithographic printing device comprises (i) a pre-sensitized lithographicribbon supply means for passing a pre-sensitized lithographic ribbon 82through one or more rollers 84 (or cylinders 66) with one end unwindingfrom a roll of unused ribbon 80 and the other end winding up to a rollof used ribbon 90, said ribbon comprising on a substrate aphotosensitive layer, (ii) an exposure means 14, and (iii) an inkingmeans 18 capable of delivering ink or both fountain solution and ink.Optionally, a transfer means 20 (not shown here) capable of transferringthe inked imaging to the receiving surface can be equipped after theinking means. Such a device requires pre-sensitized ribbon with an inkand/or fountain solution developable photosensitive layer. For a ribbonwith a photosensitive layer not developable with ink and/or fountainsolution, a developing means 16 (not shown here) may be installedbetween the exposure means and the inking means. The means 14, 16, 18,and 20 are mounted proximate the ribbon and sequentially arranged alongthe moving direction of the ribbon; and each means of 14, 16, 18, and 20completes its designed function (such as imaging, developing, inking, ortransfer) to the ribbon surface areas at the designed printing widthwhich pass by that means in each single pass during printing operation.The printing device as shown in FIG. 8 can be a regular printer with thereceiving medium passing through the printing device, or can be aprinting wheel with the printing device moving against a the receivingsurface of a stationary object. A small roller may be used to guide andpress the inked ribbon against the receiving surface, allowing theprinting of some hard-to-reach surfaces.

[0086] The ribbon substrate as used in the printing devices of FIGS. 7and 8 can be any sheet-like material that has a suitable lithographicsubstrate surface and is durable and flexible enough to undergo theunwinding and winding process. It can be a polymeric film, a paper, or ametal with or without further surface treatment such as roughening,chemical treatment, or surface coating.

[0087] The photosensitive layer on the ribbon can be any photosensitivelayer capable of hardening upon exposure to an actinic radiation. Forink and/or fountain solution developable ribbon, the photosensitivelayer is soluble or dispersible in and quickly developable with inkand/or fountain solution. All the photosensitive layer compositions asdescribed above can be used to coat the photosensitive layer on thesubstrate ribbon of FIG. 7 from a coating means. All the solid andsemisolid photosensitive layer compositions as described above can beused for the photosensitive layer of the pre-sensitized ribbon as inFIG. 8.

[0088] An interlayer between the photosensitive layer and the ribbonsubstrate can be used to, for example, enhance the development process.An overcoat on the photosensitive layer of a ribbon can be used to, forexample, to reduce oxygen inhibition. A release coating can be coated onthe back of the ribbon to prevent blocking of the photosensitive layerto the back of the ribbon.

[0089] The exposure means, developing means, inking means, and transfermeans as described above for the printing device utilizing alithographic cylinder can be used for the printing device utilizing alithographic ribbon. One or more rollers are generally provided tosupport the ribbon from the back, especially in the ink transfer areas.

[0090] The photosensitive layer should exhibit an affinity or aversionsubstantially opposite to the affinity or aversion of the substrate toat least one printing liquid selected from the group consisting of inkand an abhesive fluid for ink; the substrate can be the cylinder orribbon surface on which the photosensitive layer is coated. Abhesivefluid for ink is a fluid that repels ink; fountain solution (comprisingprimarily water) is a commonly used abhesive fluid for typical ink(Typical ink is oleophilic.) for lithographic printing. For wetlithographic printing using both fountain solution and ink, thephotosensitive layer and the substrate can be hydrophilic and oleophilicrespectively, or oleophilic and hydrophilic respectively. For waterlesslithographic printing utilizing only ink, the photosensitive layer andthe substrate can be oleophilic and oleophobic respectively, orolephobic and oleophilic respectively. An oleophilic ink (a typical ink)will selectively form inked imaging in the oleophilic areas, and ahydrophilic ink will selectively form inked imaging in the hydrophilicareas during inking process. The ink-receptive areas can be thephotosensitive layer surface in the hardened areas or the substratesurface corresponding to the non-hardened areas of the photosensitivelayer, depending on the surface properties of the photosensitive layer,the substrate, and the ink.

[0091] The lithographic printing device of this invention can be asingle color device or multicolor device. A single color printing devicecapable of printing only a single ink consists of one basic printingdevice (a printing cylinder together with all the means around it) asdescribed above. A multicolor printing device capable of printing two ormore colors consists of two or more basic printing devices as describedabove; each basic printing device prints different ink to the samereceiving surface.

[0092] This invention is further illustrated by the followingnon-limiting examples of its practice.

EXAMPLE 1

[0093] This example uses a series of experimental steps to illustratethe feasibility of the variable data lithographic printing device andprocess of the present invention.

[0094] An anodized and silicate treated aluminum sheet was wrapped onthe cylindrical surface of a cylindrical metal container having adiameter of about 20 cm and a length of about 40 cm, and was securedwith double sided tapes. The treated side of the aluminum sheet facesoutside and forms the lithographic printing cylinder surface of thisinvention.

[0095] Photosensitive layer fluid PS-1 was applied to the printingcylinder surface using a #3 Mayer rod to form a coating which covers thefull length of the cylinder surface and a width of about 10 cm along therotating direction of the cylinder surface. The coating was dried with ahot air blow drier for about 10 seconds to remove the solvent. The driedcoating has a coating weight of about 0.5 g/m². PS-1 Component Weight(g) Ebecryl RX-8301 (Oligomer from UCB Chemicals) 1.628 Sartomer SR-399(Monomer from Sartomer Company) 6.513 Pluronic L43 (Nonionic surfactantfrom BASF) 0.830 Irganox 1035 (Antioxidant from Ciba-Geigy) 0.010Triazine PP (Free radical initiator from Panchim) 1.018 Acetone 90.000

[0096] The photosensitive layer coated cylinder surface was exposedthrough a negative mask with an ultraviolet light from a 1000 wattsmercury halide lamp at a distance of about 4 inches for about 5 sec. Theexposed cylinder surface was pressed once with a cloth soaked with bothfountain solution and ink. Good inked imaging in the exposed areas andclean background in the non-exposed areas were observed. The inkedcylinder surface was then pressed against a sheet of paper. Good inkedimaging was transferred to the paper.

[0097] The inked cylinder surface was then wiped with a cloth soakedwith acetone to remove the hardened photosensitive layer as well as theleftover ink. The same cylinder surface area was repeated with the abovecoating, exposure, and inking processes; and good inked imaging wasformed on the cylinder surface. The inked imaging was then pressedagainst a different part of the same sheet of paper used in the firstprinting cycle, and good inked imaging was transferred to the paper.

EXAMPLE 2

[0098] This example is the same as EXAMPLE 1 except that the combinedinking and dampening process was replaced with separate dampening andinking process.

[0099] The exposed cylinder surface coated with photosensitive layer asabove was wiped once with a cloth soaked with fountain solution, andthen wiped once with a cloth soaked with ink. Good inked imaging in theexposed areas and clean background in the non-exposed areas wereobserved. The inked cylinder surface was then pressed against a sheet ofpaper. Good inked imaging was transferred to the paper.

I claim:
 1. A variable data lithographic printing device comprising: (a)a substrate ribbon supply means for passing a substrate ribbon throughone or more rollers with one end unwinding from a roll of unused ribbonand the other end winding up to a roll of used ribbon, said ribbonhaving a lithographic substrate surface; (b) a coating means fordepositing a photosensitive layer on the substrate ribbon surface;wherein said photosensitive layer is capable of hardening upon exposureto an actinic radiation and exhibits an affinity or aversionsubstantially opposite to the affinity or aversion of said ribbonsurface to at least one printing liquid selected from the groupconsisting of ink and an abhesive fluid for ink; (c) an exposure meansfor exposing the photosensitive layer on the ribbon with the actinicradiation according to digital imaging information to form hardenedareas in the exposed areas and non-hardened areas in the non-exposedareas; (d) an inking means for applying ink or both fountain solutionand ink to the ribbon to form inked images; (e) wherein the means (b) to(d) are mounted proximate the passage of the ribbon and sequentiallyarranged along the moving direction of the ribbon; and each means of (b)to (d) completes its designed function to the ribbon surface areas inthe designed printing width which pass by said means in each single passduring printing operation.
 2. The printing device of claim 1 whereinsaid photosensitive layer is soluble or dispersible in ink and/orfountain solution and the non-hardened areas of said photosensitivelayer are capable of being removed by contacting with ink and/orfountain solution from the inking means.
 3. The printing device of claim1 further including between the exposure means and the inking means adeveloping means for removing the non-hardened areas of thephotosensitive layer.
 4. The printing device of claim 1 furtherincluding after the inking means a transfer means for passing thereceiving medium through the printing device while pressing a receivingmedium against the inked ribbon to transfer the inked images onto thereceiving medium.
 5. The printing device of claim 1 is a printing wheelwherein the printing device moves against a receiving surface of astationary object during printing operation to transfer the inked imagesonto the receiving surface.
 6. The printing device of claim 1 whereinsaid substrate is hydrophilic and said photosensitive layer isoleophilic, and said inking means supplies both fountain solution andink.
 7. The printing device of claim 1 wherein said substrate isoleophobic and said photosensitive layer is oleophilic, and said inkingmeans supplies ink.
 8. A variable data lithographic printing devicecomprising: (a) A pre-sensitized lithographic ribbon supply means forpassing a pre-sensitized lithographic ribbon through one or more rollerswith one end unwinding from a roll of unused ribbon and the other endwinding up to a roll of used ribbon, said ribbon comprising on asubstrate a photosensitive layer wherein said photosensitive layer iscapable of hardening upon exposure to an actinic radiation and exhibitsan affinity or aversion substantially opposite to the affinity oraversion of said substrate surface to at least one printing liquidselected from the group consisting of ink and an abhesive fluid for ink;(b) an exposure means for exposing the photosensitive layer of theribbon with the actinic radiation according to digital imaginginformation to form hardened areas in the exposed areas and non-hardenedareas in the non-exposed areas; (c) an inking means for applying ink orboth fountain solution and ink to the ribbon to form inked images; (d)wherein the means (b) to (c) are mounted proximate the passage of theribbon and sequentially arranged along the moving direction of theribbon; and each means of (b) to (c) completes its designed function tothe ribbon surface areas in the designed printing width which pass bysaid means in each single pass during printing operation.
 9. Theprinting device of claim 8 wherein said photosensitive layer is solubleor dispersible in ink and/or fountain solution and the non-hardenedareas of said photosensitive layer are capable of being removed bycontacting with ink and/or fountain solution from the inking means. 10.The printing device of claim 8 further including between the exposuremeans and the inking means a developing means for removing thenon-hardened areas of the photosensitive layer.
 11. The printing deviceof claim 8 further including after the inking means a transfer means forpassing a receiving medium through the printing device while pressingthe receiving medium against the inked ribbon to transfer the inkedimages onto the receiving medium.
 12. The printing device of claim 8 isa printing wheel wherein the printing device moves against a receivingsurface of a stationary object during printing operation to transfer theinked images onto the receiving surface.
 13. The printing device ofclaim 8 wherein said substrate is hydrophilic and said photosensitivelayer is oleophilic, and said inking means supplies both fountainsolution and ink.
 14. The printing device of claim 8 wherein saidsubstrate is oleophobic and said photosensitive layer is oleophilic, andsaid inking means supplies ink.
 15. A variable data lithographicprinting device comprising: (a) A pre-sensitized lithographic ribbonsupply means for passing a pre-sensitized lithographic ribbon throughone or more rollers with one end unwinding from a roll of unused ribbonand the other end winding up to a roll of used ribbon, said ribboncomprising on a hydrophilic substrate an oleophilic photosensitive layerwherein said photosensitive layer is soluble or dispersible in inkand/or fountain solution and capable of hardening upon exposure to anactinic radiation; (b) an exposure means for exposing the photosensitivelayer of the ribbon with the actinic radiation according to digitalimaging information to form hardened areas in the exposed areas andnon-hardened areas in the non-exposed areas; (c) an inking means forapplying fountain solution and ink to the ribbon to remove thenon-hardened areas of the photosensitive layer and to form inked imagesin the hardened areas; (d) wherein the means (b) to (c) are mountedproximate the passage of the ribbon and sequentially arranged along themoving direction of the ribbon; and each means of (b) to (c) completesits designed function to the ribbon surface areas in the designedprinting width which pass by said means in each single pass duringprinting operation.
 16. The printing device of claim 15 furtherincluding after the inking means a transfer means for passing thereceiving medium through the printing device while pressing thereceiving medium against the inked ribbon to transfer the inked imagesonto the receiving medium.
 17. The printing device of claim 15 is aprinting wheel wherein the printing device or the ribbon surface movesagainst the receiving surface of a stationary object during printingoperation to transfer the inked images onto the receiving surface. 18.The printing device of claim 15 wherein said actinic radiation is aninfrared, visible or ultraviolet laser.
 19. The printing device of claim15 wherein said photosensitive layer comprises a polymerizable monomerand an initiator.
 20. The printing device of claim 15 wherein saidphotosensitive layer comprises a polymerizable monomer, an initiator,and an actinic light absorbing dye.
 21. The printing device of claim 15wherein said ribbon further comprises an ink and/or fountain solutionsoluble or dispersible interlayer between the substrate and thephotosensitive layer.
 22. The printing device of claim 15 wherein saidribbon further comprises an ink and/or fountain solution soluble ordispersible overcoat on the photosensitive layer.